This invention relates to an apparatus for making a subterranean tunnel, comprising a head having in its turn a body and a nose mounted thereon and provided on at least one side with an abutment face which may make an angle with the geometrical axis of the body, at least one nozzle mounted on the nose and directed away from said body and a duct for fluid under pressure connected to said nozzle.
Apparatuses of this kind are used among other things for making or boring tunnels extending substantially in horizontal direction. Such tunnels serve for the installation of so-called utility piping.
The fluid under pressure injected through the nozzle loosens the soil in front of the nose, and the direction of advance of the head in the ground and hence the direction of the tunnel bored depend substantially on the direction of the abutment face relative to the body.
The term "boring" as used herein is therefore to be construed in the broadest sense, and does not necessarily connote a rotating movement e.g. of a boring tool. Boring can also mean the squirting away and/or the displacement of the soil.
The abutment face is necessary for orienting the head somewhere in the ground, for it happens that certain obstacles, such as a watercourse, have to be avoided.
In a known apparatus for subterraneous boring, the nose, having an abutment face inclined to the axis of the body at one side only is integral with said body, and rods are provided for rotating the body and the nose around the longitudinal axis.
When during the advancement of the boring head and the injection of fluid under pressure, said head is rotated, it is displaced straight on in the same direction wherein it is being pushed. When during pushing, the boring head is not rotated, however, the head pushes itself off by means of the abutment face relatively to the ground and deviates from the pushing direction in the sense away from said abutment face. When the abutment face is at the underside, the boring head moves upwardly.
Not only does this known apparatus fail to provide for accurate steering, but it also restricts the possibilities of using the apparatus. Thus no rectilinear boring is possible without rotating the boring head. It is not possible to deviate from this boring direction with a rotating head or nose. Also the necessity to use rigid rods for rotating the head constitutes an impediment to the choice of the means for advancing the head. This cannot be effected e.g. with flexible hoses or tubes.
It is an object of the present invention to remove these drawbacks and to provide an apparatus of the above described type, wherein the head can be steered in a very simple and accurate manner and which offers an ample range of applications and wherein, for one thing, the boring direction does not depend on whether the head is or is not rotated during the driving of the boring head.